The instrument panel (or cluster) of a vehicle is generally considered an unsuitable environment for an electronic compass. An electronic compass integrated into an instrument panel of a vehicle will detect a variety of magnetic disturbances that can affect the compass reading. Interfering magnetic fields are caused by various vehicle subsystems, such as, a motor for the vehicle HVAC system, an audio system, etc., and typically vary in magnitude. One significant source of interfering magnetic fields are stepper motors that are used to drive needles of gauges in the instrument panel for various vehicle functions such as speed, rpm, oil pressure, fuel level, and so on. Stepper motors for the instrument display gauges may be in close proximity to the magnetic sensors of the electrical compass integrated into an instrument panel of a vehicle. Therefore, there is a need for a system and method to compensate for the magnetic disturbance caused by motors such as stepper motors.
Prior solutions characterize a magnetic disturbance produced by a vehicle accessory, such as a stepper motor, as a constant magnetic offset that changes little as the vehicle is used. Accordingly, an offset for each vehicle accessory is measured or calculated and stored in memory. The constant magnetic offset may then be accessed when a particular subsystem is in operation.